Research on the directly driven permanent magnet synchronous generator connected to DC grid

With the development of the wind energy and in-depth study of DC grid, research on wind energy connecting to DC grid is piling up. After comparing the power losses, generating efficiency and control performance of two types of wind generator, the paper comes to a conclusion that directly driven permanent magnetic synchronous generator (PMSG) is the better type for DC grid connection. Then the author discusses two conversion methods and chooses the connection to DC gird through PWM rectifier. And then the paper gives the MPPT strategy for DC grid integration. The DC bus voltage stability problem caused by wind energy fluctuation is solved through bidirectional energy flow control of super-capacitor with DC/DC converter. Finally, the paper builds a simulating system to give a confirmation of the proposed control policy for PMSG connecting to DC grid.